With a treatment goal of 400 patients, the objective of the multicentre study is to assess the long-term safety and efficacy of Xoft's Axxent Electronic Brachytherapy System for the treatment of early-stage breast-cancer patients. The Axxent system - a tiny X-ray source that's small enough to insert into the body - delivers high-dose-rate radiation treatment without the use of radioactive isotopes.
Axxent is based around a miniaturized (2.25 mm diameter) X-ray source that delivers localized and targeted radiation treatment. Unlike radionuclide-based brachytherapy sources, the radiation can be switched on and off as required. The lower energies involved remove the need for expensive shielding, while the lack of radioactive material eliminates the complex logistics associated with handling isotopes.
The primary endpoint of EXIBT is the measurement and quantification of skin and subcutaneous toxicities through five year follow-up. Additional evaluation will include a quality-of-life questionnaire based on patient experience. Secondary endpoints will assess local-regional breast failure and patient survival through five years as well as device performance.
"For many women, post-lumpectomy radiation therapy can now be completed in one week with brachytherapy compared to the six to seven weeks required for external-beam therapy," said Peter Beitsch, co-principal investigator of EXIBT and the surgeon for the first patient on the registry.
He added: "The fact that three physician organizations involved in the treatment of breast cancer - ASBrS, ABS and ACRO - have agreed to jointly provide oversight for the Electronic Brachytherapy patient registry speaks to the multidisciplinary nature of breast-brachytherapy treatment decisions and the potential impact this new method of delivering non-radioactive, non-isotope-based radiation treatment may have on patients."
• In an international patent application filed last year, Xoft detailed a brachytherapy system that monitors the delivered dose and uses this information to tailor the radiation delivery in real time (WO/2007/120532). In one procedure, mapping is used to determine the shape and location of the region to be irradiated and a treatment plan is developed based on this information and a dose prescription. While the radiation is delivered to the target region internally, the dose received at various points in and around the target is monitored and continually fed to a central processor. Based on this feedback, the system modifies the treatment plan and radiation delivery in order to deliver the prescribed dose at all locations.